I made a lego hand cannon when i was bored(you can reload like most of handcannons in destiny(if you want too see write in comment) and it shoots but not very well) :
✓ LEGO How to make A CANNON! | WORKING - YouTube
Custom Cannon Revolutionary War Civil War Cavalry War of 1812 - Etsy Israel
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LEGO Pirate Red Cannon Lot - Red Shooting Cannons (for minifigs) | Walmart Canada